Akryum/vue-virtual-scroller ? reverse-engineered prompt

Build me a Vue 3 virtual scrolling component library that makes long lists feel fast even with huge amounts of data.

I want a simple, polished package I can drop into a Vue app to render large lists and grids without lag, with smooth scrolling and support for items that may have different heights. Make it easy to use in a real app, and include a small demo or docs page that shows how to wire it up and what it looks like with lots of data.

Keep it modern and compatible with an ESM aware setup like Vite or Nuxt, and if you need to check anything about current Vue docs or best practices, look them up online. Also add a few basic tests so I can trust it works.